1. Field of the Invention
This invention relates to a vehicle automatic transmission control system, more particularly to such a system in which the intention of the driver is inferred and the control values are determined on the basis of parameters including the inferred value.
2. Description of the Prior Art
People today no longer consider vehicles to be simply transporters but want a vehicle that provides operability and controllability matched to human sensibilities. For example, the driver of a vehicle equipped with an automatic transmission wants and expects operability and controllability on a level with a vehicle having a manual transmission when it is operated by an expert driver, even when driving through mountainous areas. For meeting this desire, the assignee has developed a wide range of technologies relating to vehicle automatic transmission control systems using fuzzy logic. These are disclosed, for example, in Japanese Laid-open Patent Publications No. 2(1990)-3739 and No. 2(1990)-85563 (also filed in the United States to mature as U.S. Pat. No. 5,036,730 and filed in EPO under 89306192.9); No. 2(1990)-3738 (also filed in the United States to mature as U.S. Pat. No. 5,079,705 and filed in EPO under 89306167.1); No. 2(1990)-138,558 and No. 2(1990)-138,561 (also filed in the United to mature as U.S. Pat. No. 5,067,374 and filed in EPO under 89311976.8); No. 2(1990)-138,559, No. 2(1990)-138,560 and No. 2(1990)-150,558 (also filed in the United States to mature as U.S. Pat. No. 5,079,704 and filed in EPO under 89311970.1); and No. 4(1992)-8964 (also filed in the United States under Ser. No. 691,066 and EPO under 91303878.2).
For achieving the desired sophisticated control matched to the sensibilities of the driver it is preferable to conduct reasoning for inferring the driver's intention and then to determine the control values based on various parameters including the inferred value. To this end, as disclosed in aforesaid Japanese Laid-open Patent Publication No. 4(1992)-8964 (U.S. Ser. No. 691,066), the assignee developed a control system in which fuzzy reasoning is used for inferring the driver's intention to decelerate from the engine load and the amount of vehicle acceleration/deceleration.
An object of the invention is to provide a vehicle automatic transmission control system that is an improvement on the system developed earlier by the assignee, specifically a vehicle automatic transmission control system which ascertains the intention of the driver with increased precision is thus able to achieve sophisticated shift scheduling well matched to the sensibilities of the driver.
Another object of the invention is to provide a vehicle automatic transmission control system which by ascertaining the intention of the driver is able to achieve control faithful to the driver's intention.
For realizing these objects, the present invention provides a system for controlling a multi-step geared or continuously variable automatic transmission of a vehicle, including first means for determining parameters at least indicative of an engine load, a vehicle speed and a driving resistance, second means for carrying out a first fuzzy reasoning to infer a value indicative of the driver's intention to decelerate or accelerate and third means for carrying out a second fuzzy reasoning using the parameters and the inferred values to determine a gear ratio to be shifted to. In the system, the improvement comprises said second means carries out the first fuzzy reasoning at least using parameters indicative of an engine load and a parameter indicating if the vehicle is hill climbing or hill descending.